1. Field of the Invention
This invention relates to a disk apparatus having a rotary type actuator to move a head onto a disk. More particularly, this invention relates to a magnetic disk apparatus having a rotary type actuator using a return spring for positioning a magnetic head of the actuator at a predetermined position in a rotational direction about a center axis of the actuator.
2. Description of the Related Art
In a disk apparatus, such as a magnetic disk apparatus, a head to read from and/or write data to a disk needs to be positioned at a predetermined zone on a surface of the disk in the event operation of the disk apparatus is disabled, such as disablement due to damage, power failure or some other breakdown of the apparatus power supply. More particularly, in a magnetic disk apparatus, magnetic heads are positioned in a so-called magnetic head landing zone or contact start-stop ("CSS") zone provided on the surface of the magnetic disk. The CSS zone is used as an initial track position when the magnetic head carrier carries out a contact start-stop operation in the magnetic disk apparatus. The CSS zone is usually provided at the most inner or outer circumferential track position of the magnetic disk.
FIG. 7 is a vertical cross-sectional view of a magnetic disk apparatus having a prior art rotary actuator. As shown in FIG. 7, the magnetic disk apparatus 10 comprises a disk housing or enclosure 12, a spindle assembly 14, and a rotary actuator 16.
The spindle assembly 14 comprises a plurality of magnetic disks 18, a spindle motor 20, and a center spindle shaft 22. The magnetic disks 18 are mounted on the spindle shaft 22 through spacers 24 located between the magnetic disks 18. The spindle shaft 22 is mountably supported by the disk enclosure 12. Shaft bearings 26,28 are located at each end of the spindle shaft 22 for rotatably supporting shaft 22. The spindle shaft 22 is operatively driven and rotated by the spindle motor 20.
The rotary actuator 16 comprises a center shaft 30, a carriage 32, a plurality of magnetic heads 34, magnetic head arms 42 and a coil assembly 36. The center shaft 30 is mountably supported by the disk enclosure 12. Shaft bearings 38,40 are located at each end of the center shaft 30 for rotatably supporting the shaft 30. The carriage 32 is provided around and integrally connected to the center shaft 30. The magnetic heads 34 read and/or write data onto corresponding magnetic disks 18. Each of the heads 34 is mounted on a corresponding head arm 42. The head arms 42 are fixed to the carriage 32. Each of the magnetic heads 34 is positioned opposite to a corresponding surface of a magnetic disk 18. The coil assembly 36 is also fixed to the carriage 32 and constitutes part of a magnetic circuit 44 that rotates the carriage 32 with the center shaft 30. The magnetic circuit 44 also has a yoke 46 provided on an inside surface of the disk enclosure 12, and permanent magnets 48a,48b separated by an air space.
A return spring 50, i.e., a coil spring, is provided at an end of the center shaft 30 and in between the bearing 38 and the disk enclosure 12. One end of the coil spring 50 is fixed to the center shaft 30 and the other end of the coil spring 50 is fixed to the disk enclosure 12. Each end of the coil spring 50 is bent, and these bent ends are positioned in respective slits formed on the center shaft 30 and the disk enclosure 12.
As explained above, the coil spring 50 has been conventionally provided at the end of the center shaft 30. Therefore, where the rotary actuator 16 is used in a disk apparatus, such as a magnetic disk apparatus 10, the disk apparatus requires extra space for locating the spring.